Field installed fiber optic connector

ABSTRACT

The present disclosure relates to a field installable connector system. The connector system includes a factory terminated subassembly including a ferrule terminating an optical fiber of an optical fiber cable. The factory terminated subassembly has a small transverse cross-section to facilitate routing through a duct. The connector system also includes a field installable subassembly including various connector components that can be installed after the factory terminated subassembly has been routed through a duct. The components can be sealed and hardened.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.16/807,810, filed on Mar. 3, 2020, now U.S. Pat. No. 10,976,500, whichis a Continuation of U.S. patent application Ser. No. 16/063,192, filedon Jun. 15, 2018, now U.S. Pat. No. 10,641,970, which is a NationalStage Application of PCT/US2016/066952, filed on Dec. 15, 2016, whichclaims the benefit of U.S. Patent Application Ser. No. 62/268,418, filedon Dec. 16, 2015, the disclosures of which are incorporated herein byreference in their entireties. To the extent appropriate, a claim ofpriority is made to each of the above disclosed applications.

TECHNICAL FIELD

The present disclosure relates to fiber optic data transmission, andmore particularly to fiber optic cable connection systems.

BACKGROUND

Fiber optic cables are widely used to transmit light signals for highspeed data transmission. A fiber optic cable typically includes: (1) anoptical fiber or optical fibers; (2) a buffer or buffers that surroundsthe fiber or fibers; (3) a strength layer that surrounds the buffer orbuffers; and (4) an outer jacket. Optical fibers function to carryoptical signals. A typical optical fiber includes an inner coresurrounded by a cladding that is covered by a coating. Buffers (e.g.,loose or tight buffer tubes) typically function to surround and protectcoated optical fibers. Strength layers add mechanical strength to fiberoptic cables to protect the internal optical fibers against stressesapplied to the cables during installation and thereafter. Examplestrength layers include aramid yarn, steel and epoxy reinforced glassroving. Outer jackets provide protection against damage caused bycrushing, abrasions, and other physical damage. Outer jackets alsoprovide protection against chemical damage (e.g., ozone, alkali, acids).

Fiber optic cable connection systems are used to facilitate connectingand disconnecting fiber optic cables in the field without requiring asplice. A typical fiber optic cable connection system forinterconnecting two fiber optic cables includes fiber optic connectorsmounted at the ends of the fiber optic cables, and a fiber optic adapterfor mechanically and optically coupling the fiber optic connectorstogether. Fiber optic connectors generally include ferrules that supportthe ends of the optical fibers of the fiber optic cables. The end facesof the ferrules are typically polished and are often angled. The fiberoptic adapter includes co-axially aligned ports (i.e., receptacles) forreceiving the fiber optic connectors desired to be interconnected. Thefiber optic adapter includes an internal sleeve that receives and alignsthe ferrules of the fiber optic connectors when the connectors areinserted within the ports of the fiber optic adapter. With the ferrulesand their associated fibers aligned within the sleeve of the fiber opticadapter, a fiber optic signal can pass from one fiber to the next. Theadapter also typically has a mechanical fastening arrangement (e.g., asnap-fit arrangement) for mechanically retaining the fiber opticconnectors within the adapter. One example of an existing fiber opticconnection system is described at U.S. Pat. Nos. 6,579,014, 6,648,520,and 6,899,467.

Hardened (e.g., ruggedized) fiber optic connection systems are oftenused for outside environments. Hardened fiber optic connection systemsare typically environmentally sealed and include robust connectioninterfaces capable of accommodating relatively large pulling loads. Atypical hardened connector includes a twist-to-lock fastener (e.g., athreaded fastener, a bayonet type fastener or like fastener) thatengages a mating twist-to-lock interface defined by a correspondinghardened fiber optic adapter to securely retain the hardened connectorwithin the hardened adapter. Example hardened connection systems aredisclosed by U.S. Pat. Nos. 7,572,065; 7,744,288; and 7,090,406. Typicalhardened fiber optic connectors are typically more bulky and robust thantheir non-hardened counterparts.

When installing a fiber optic network, it is often desired to routefiber optic cable through ducts (e.g., underground ducts, ducts inbuildings, etc.). It is also desirable to use pre-terminated connectorson fiber optic cables so that termination operations can be efficientlyand precisely performed in a factory environment rather than beingperformed in the field. However, since fiber optic connectors arerelatively large, typical cables with pre-terminated connectors cannotreadily be routed through ducts. This issue is particularly problematicfor hardened connectors due to their relatively large size. Improvementsare needed in this area.

SUMMARY OF THE DISCLOSURE

The present disclosure relates to a field installable connector system.The connector system includes a factory terminated subassembly includinga ferrule terminating an optical fiber of an optical fiber cable. Thefactory terminated subassembly has a small transverse cross-section tofacilitate routing through a duct. The connector system also includes afield installable subassembly including various connector componentsthat can be installed after the factory terminated subassembly has beenrouted through a duct. The components can be sealed and hardened.

A variety of additional inventive aspects will be set forth in thedescription that follows. The inventive aspects can relate to individualfeatures and to combinations of features. It is to be understood thatboth the forgoing general description and the following detaileddescription are exemplary and explanatory only and are not restrictiveof the broad inventive concepts upon which the embodiments disclosedherein are based.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a factory terminated subassembly in accordance withprinciples of the present disclosure;

FIG. 2 is a longitudinal cross-sectional view of the factory terminatedsubassembly of FIG. 1;

FIG. 3 is a cross-sectional view taken along section line 3-3 of FIG. 2;

FIG. 4 shows the factory terminated subassembly of FIG. 1 in the processof being mounted within a protective carrier;

FIG. 5 shows the factory terminated subassembly of FIG. 1 fully enclosedwithin the carrier;

FIG. 6 shows a kit for a field installable subassembly for convertingthe factory terminated subassembly of FIG. 1 into a hardened fiber opticconnector;

FIG. 7 shows a first installation step for installing the fieldinstallable subassembly of FIG. 6 over the factory terminatedsubassembly of FIG. 1, the factory terminated subassembly is showninserted through a hardened coupling element;

FIG. 8 shows a second step installing the field installable subassemblyof FIG. 6 over the factory terminated subassembly of FIG. 1, a pluglocator is shown inserted over an optical cable of the factoryterminated subassembly;

FIG. 9 shows a third step for installing the field installablesubassembly of FIG. 6 over the factory terminated subassembly of FIG. 1,the plug locator is shown inserted into a front end of the hardenedcoupling element;

FIG. 10 shows a fourth step for installing the field installablesubassembly of FIG. 6 over the factory terminated subassembly of FIG. 1,in this step a plug body is shown placed in coaxial alignment with thefactory terminated subassembly;

FIG. 11 shows a fifth step for installing the field installablesubassembly of FIG. 6 over the factory terminated subassembly of FIG. 1,the plug body is shown inserted over the factory terminated subassemblysuch that the ferrule of the factory terminated subassembly protrudesthrough a front end of the plug body;

FIG. 12 shows a sixth step for installing the field installablesubassembly of FIG. 6 over the factory terminated subassembly of FIG. 1,in this step the plug body is placed in coaxial alignment with a plugmount defined by the plug locator;

FIG. 13 shows a seventh step for installing the field installablesubassembly of FIG. 6 over the factory terminated subassembly of FIG. 1,in this step the plug body is snapped over the plug mount of the pluglocator;

FIG. 14 shows an eighth step for installing the field installablesubassembly of FIG. 6 over the factory terminated subassembly of FIG. 1,in this step a seal enlargement tube has been removed from a back end ofan elastomeric seal mounted at a rear end of the hardened couplingelement thereby allowing the elastomeric seal to elastically radiallyconstrict upon the optical fiber cable of the factory terminatedsubassembly so as to provide a seal between the hardened couplingelement and the fiber optic cable;

FIG. 15 shows an alternative seal enlargement tube having an elongatedlength suitable for providing mechanical protection across a transitionbetween the back end of the elastomeric seal and a duct;

FIG. 16 illustrates an example of a ruggedized fiber optic adapterconfigured to mate with the assembled hardened fiber optic connector ofFIG. 14;

FIG. 17 illustrates another kit for a field installable subassemblyadapted to be mounted over the factory terminated subassembly of FIG. 1;

FIG. 18 is a first step for installing the field installable subassemblyof FIG. 17 over the factory terminated subassembly of FIG. 1, in thisstep a hardened coupling element is inserted over the factory terminatedsubassembly;

FIG. 19 shows a second step for installing the field installablesubassembly of FIG. 17 over the factory terminated subassembly of FIG.1, in this step a rear connector housing has been mounted over the fiberoptic cable of the factory terminated subassembly of FIG. 1;

FIG. 20 illustrates a third step for installing the field installablesubassembly of FIG. 17 over the factory terminated subassembly of FIG.1, in this step a plug body is placed in coaxial alignment with thefactory terminated subassembly;

FIG. 21 illustrates a fourth step for installing the field installablesubassembly of FIG. 17 over the factory terminated subassembly of FIG.1, in this step the plug body is inserted over the factory terminatedsubassembly such that a ferrule of the factory terminated subassemblyprojects through a front end of the plug body;

FIG. 22 shows a fifth step for installing the field installablesubassembly of FIG. 17 over the factory terminated subassembly of FIG.1, in this step the rear housing is secured to the plug body with therear housing functioning as a spring stop;

FIG. 23 shows a sixth step for installing the field installablesubassembly of FIG. 17 over the factory terminated subassembly of FIG.1, in this step a plug locator is mounted over the assembled plug bodyand rear housing;

FIG. 24 shows a seventh step for installing the field installablesubassembly of FIG. 17 over the factory terminated subassembly of FIG.1, in this step the plug locator is inserted into a front end of thehardened coupling element;

FIG. 25 shows another factory terminated subassembly in accordance withthe principles of the present disclosure, the subassembly include aferrule hub on which a tuning key mounts; and

FIG. 26 is a cross sectional view of the field installable subassemblyof FIGS. 6-14 installed over the factory terminated subassembly of FIG.1.

DETAILED DESCRIPTION

Aspects of the present disclosure relate to systems that are factoryterminated that can also be readily deployed through ducts. In certainexamples, the system can include a factory terminated subassemblyincluding a ferrule mounted at the terminal end of an optical fiber of afiber optic cable. The factory terminated subassembly can also include ahub supporting the ferrule. The fiber optic cable can include one ormore tensile strength members that are anchored within the ferrule hub.The factory terminated subassembly can further include a spring mountedbehind the ferrule hub and over the fiber optic cable. As used herein,“factory terminated” means that a ferrule is installed on a fiber of acable at the factory. This can include direct terminations when theoptical fiber of a cable is extended continuously to the ferrule, orsplice-on terminations where the ferrule supports a stub optical fiberthat is spliced to the optical fiber of the fiber optic cable.

Aspects of the present disclosure also relate to field installablesubassemblies having fiber optic connector components (e.g., housings,shells, seals, keys, plugs, etc.) that can be quickly and easily mountedover the factory terminated subassemblies in the field. It will beappreciated that the factory terminated subassemblies can have maximumcross-sectional dimensions that are substantially smaller than thetransverse cross-sectional dimensions defined by the assembled fieldinstallable subassembly. The small size of the factory terminatedsubassembly allows the factory terminated subassembly to be readilyrouted through a duct in the field. Examples of various pushingtechniques for use with the protective arrangement 500 are shown in U.S.Application No. 62/268,379, filed herewith, and titled “Arrangements forPushing and Pulling Cables; and Methods,” the disclosure of which isincorporated herein by reference. Once the factory terminatedsubassembly with its corresponding fiber optic cable has been routedthrough a duct, the field installable subassembly can be easily mountedover the factory terminated subassembly without requiring a skilledartisan. Additionally, it will be appreciated that the factoryterminated subassembly can be compatible with a number of differentcategories/types of field installable subassemblies each correspondingto a different style or type of connector. The different types ofconnectors can include hardened and non-hardened. Thus, once the factoryterminated subassembly has been routed through a given duct, theinstaller can select from a number of different connector styles so thatthe factory terminated subassembly can be converted into a fiber opticconnector that is compatible with the type of fiber adapter encounteredin the field.

FIG. 1 illustrates an example factory terminated subassembly 20 inaccordance with the principles of the present disclosure. The factoryterminated subassembly 20 includes a fiber optic cable 22, a spring 24,and a ferrule assembly 26. The ferrule assembly 26 includes a ferrule28, a ferrule hub 30 mounted at a base end of the ferrule 28 and dustcap 32 mounted over a free end of the ferrule 28. The fiber optic cable22 is preferably anchored to the ferrule hub 30.

In certain examples, the fiber optic cable 22 is relatively flexiblewhile still exhibiting substantial tensile strength. As shown at FIGS. 2and 3, the fiber optic cable 22 includes an outer jacket 34 containingan optical fiber 36. The fiber optic cable 22 can also include at leastone strength member 38 enclosed within the outer jacket 34. In certainexamples, the strength member 38 can include a strength layer thatsurrounds the optical fiber 36 and forms a barrier between the opticalfiber and the outer jacket 34. In certain examples, strength member 38can include a tensile reinforcing element such as a yarn that providestensile reinforcement while concurrently providing minimal compressivereinforcement. In certain examples, the strength member 38 can includeone or more aramid yarns. An example configuration for the fiber opticcable 22 is disclosed by U.S. Pat. No. 8,548,293, which is herebyincorporated by reference. In certain examples, fiber optic cable 22 hasan outer diameter less than 2 mm, or less than 1.8 mm, or less than orequal to 1.5 mm.

In certain examples, the ferrule 28 can define a central fiber passage40. An optical fiber section 35 can be secured (e.g., adhesively bonded)within the fiber passage 40 at the factory. The optical fiber section 35can be optically coupled to the optical fiber 36 either by a splice orby a continuous integral coupling. Thus, the optical fiber section 35can be considered part of the optical fiber regardless of whether asplice is used or not. Additionally, distal end faces of the opticalfiber section 35 and the ferrule 28 can be processed (e.g., polished,angled, etc.) at the factory. As indicated above, the fiber optic cable22 is preferably anchored to the ferrule hub 30. In certain examples,the strength members 38 of the fiber optic cable 22 can be coupled tothe interior of the ferrule hub 30 via an adhesive material such asepoxy. In certain examples, the ferrule 28 can be an SC ferrule. Inother examples, other types of ferrules such as LC ferrules may be used.

The ferrule hub 30 includes a flange 42 defining a plurality of discretecircumferential position indicators that are positionedcircumferentially about a central longitudinal axis of the ferrule 28.As depicted, the circumferential position indicators include a pluralityof flats 43 positioned circumferentially about the central longitudinalaxis of the ferrule 28. In certain examples, the flats 43 are configuredto provide the hub flange with a hexagonal transverse cross-sectionalshape.

A typical single fiber optical connector includes a ferrule having anouter cylindrical surface that functions as a reference surface when theferrule is received within an alignment sleeve of a fiber optic adapter.The ferrule also defines a central axial passageway in which the opticalfiber is secured. Ideally, the optical fiber is secured in the centralaxial passageway with the fiber core perfectly concentric with the outercylindrical surface of the ferrule. However, due to manufacturingtolerances, the fiber core is not typically perfectly concentric withthe outer cylindrical surface. This is because, among other things, theferrule passageway may not be concentric with the ferrule outercylindrical surface, the optical fiber may not be centered in theferrule passageway, and the fiber core may not be centered within thefiber cladding that defines an outer surface of the optical fiber. Thislack of concentricity between the fiber core and the ferrule outercylindrical surface causes fiber core eccentricity. Fiber coreeccentricity can be defined as the distance between the centrallongitudinal axis of the fiber core (i.e., the fiber core axis) and thecentral longitudinal axis defined by the ferrule outer cylindricalsurface (i.e., the ferrule axis). The direction that the fiber core axisis offset from the ferrule axis can be referred to as the direction ofcore eccentricity.

Due to fiber core eccentricity, signal losses within a system can occurat the connection between two optical fibers. This is because fiber coreeccentricity prevents the fiber cores of the optical fibers beingoptically coupled together from being perfectly co-axially aligned. Theworst-case scenario occurs when the ferrules of two fiber opticconnectors being coupled together have directions of core eccentricitythat are 180 degrees out of phase with respect to each other. Tominimize the negative effect of fiber core eccentricity with respect tosignal loss, it is desirable to position the directions of coreeccentricity of the ferrules of fiber optic connectors being coupledtogether in the same rotational orientation. This can be accomplished by“tuning” fiber optic connectors during manufacturing such that thedirection of core eccentricity is the same for all of the fiber opticconnectors. Tuning typically involves rotating the ferrule tointentionally position the direction of core eccentricity of the ferruleat a particular rotational orientation relative to one or more keyedcomponents of the fiber optic connector. Example tuning techniques aredisclosed at PCT Publication No. WO 02/052310 and at U.S. Pat. No.5,212,752, which are hereby incorporated by reference.

The discrete circumferential position indicators (e.g., the flats 43)provided on the hub 30 provide a means for allowing the factoryterminated subassembly 20 to be tuned in the field. Specifically, in thefactory, a core offset of the fiber core relative to the ferrule 28 canbe determined. Once the core offset has been determined, acircumferential position indicator corresponding to the core offset canbe marked so that the core offset can be readily identified in thefield. In one example, the circumferential position indicator inalignment with the core offset direction can be marked. In anotherexample, the circumferential position indicator offset 180° from thecore offset direction can be marked. As long as a predeterminedrelationship between the arcing and the core offset is maintained, thedirection of core offset can readily be determined in the field. Thus,when the ferrule assembly is loaded into a connector plug in the field,the installer can identify the core offset direction and make sure theferrule assembly is loaded into the plug at the proper rotationalorientation for the connector to be properly tuned.

Referring to FIGS. 4 and 5, a casing 50 can be installed over theferrule assembly 26 and the spring 24 in the factory. The casing 50 canbe configured to protect the ferrule assembly 26 and the spring 24 asthe fiber optic cable 22 is pushed or pulled through a duct.Additionally, the casing 50 can include an eye 52 (i.e., an opening) forfacilitating connecting the casing 50 to a pulling or pushing member.Moreover, a front end 54 of the casing 50 can be rounded to facilitatedirecting the casing 50 through curved paths defined by ducts.

FIG. 6 shows a kit 60 including a field installable subassembly 62adapted to be mounted over the factory terminated subassembly 20. Thefield installable subassembly 62 is adapted to convert the factoryterminated subassembly 20 into a hardened fiber optic connector. Thefield installable subassembly 62 includes housing 64 having a front end66 and a back end 68. In one example, the housing can be generallycylindrical. In use, the housing 64 can function as a sealed housing. Anelastomeric sealing sleeve 70 is mounted over the back end 68 of thehousing 64 so as to provide a seal therewith. In certain examples, theelastomeric sealing sleeve 70 has an elastomeric construction. In oneexample, the elastomeric sealing sleeve 70 has a composition thatincludes a material such as silicone rubber. An annular seal 72 is alsoprovided adjacent the front end of the housing. The seal 72 can bemounted within a groove 73 defined by the housing 64.

The subassembly 62 also includes a hardened coupling element 65 mountedon the housing 64. In certain examples, the coupling element 65 can turn(i.e., rotate) relative to the housing 64 about a longitudinal axis ofthe housing 64. The hardened coupling element 65 further includes atwist-to-lock coupling interface 74. As depicted, the twist-to-lockcoupling interface 74 includes a plurality of external threads adaptedto mate with corresponding internal threads 89 of a hardened fiber opticadapter 90 (see FIG. 16). In other examples, the twist-to-lock couplinginterface can include a bayonet-type interface, a partial threadedinterface or other types of robust coupling interfaces. A front end ofthe coupling element 65 abuts against a shoulder 67 of the housing 64near the front end of the housing 64.

The fiber optic adapter 90 includes a first port 91 for receiving afirst fiber optic connector (e.g., the hardened connector that resultsfrom the combination of the factory terminated subassembly 20 and thefield installable sub assembly 62) and an opposite second port 92 forreceiving a second fiber optic connector. The internal threads 89 aredefined within the first port 91. An adapter sleeve (not shown) foraligning the ferrules of the connectors is positioned within the fiberoptic adapter 90. When the first and second connectors are mountedwithin the first and second ports 91, 92, the ferrules of the first andsecond connectors are received in the adapter sleeve and co-axiallyaligned with one another such that optical signals can be transferredbetween the first and second connectors. Further details regarding thefiber optic adapter 90 are disclosed in U.S. Pat. No. 6,579,014 that ishereby incorporated by reference in its entirety.

A seal expansion tube 76 is pre-inserted through a back end of theelastomeric sealing sleeve 70 and into the interior of the housing 64.The seal expansion tube 76 preferably has an inner diameter that islarger than a maximum transverse cross-sectional dimension of theferrule assembly 26 and is also larger than a maximum transversecross-sectional dimension of the protective casing 50. Thus, the sealexpansion tube 76 retains a rear end of the elastomeric sealing sleeve70 in an enlarged orientation so that the elastomeric sealing sleeve 70does not interfere with insertion of the factory terminated subassembly20 through the housing 64. It will be appreciated that the elastomericsealing sleeve 70 has a physical construction that elastically urges theelastomeric sealing sleeve 72 toward an orientation in which an innerdiameter defined by the elastomeric sealing sleeve 70 is smaller than anouter diameter of the fiber optic cable 22. Therefore, once the sealexpansion tube 76 is removed from the elastomeric sealing sleeve 70, theelastomeric sealing sleeve 70 elastically returns to a constrictedorientation in which the elastomeric sealing sleeve 70 is capable offorming a fluid tight seal about the exterior of the fiber optic cable22.

The field installable subassembly 62 further includes a plug locator 78that mounts within the front end 66 of the housing 64. The plug locator78 can include a longitudinal slot 80 that extends through the length ofthe plug locator 78. The longitudinal slot is configured to allow theplug locator 78 to be inserted laterally over the fiber optic cable 22.The plug locator 78 further includes opposite paddles 82 and 84 thatprovide a keying function when the fiber optic connector is mated withits corresponding fiber optic adapter 90 (see FIG. 16). The plug locator78 further includes a plug mount 86 adapted to coaxially align with acentral axis of the hardened coupling element 64. The plug mount 86defines a through slot 88 for allowing the fiber optic cable 22 to passlaterally into an interior of the plug mount 86. The plug mount 86further includes one or more snap-fit structures 90. In certainexamples, the plug mount 86 can also include a surface 87 that functionsas a spring stop.

Referring back to FIG. 6, the field installable subassembly 62 furtherincludes a plug body 92. In certain examples, the plug body 92 can havean SC type form factor. The plug body 92 includes one or more snap-fitstructures 94 that mate with the snap-fit structures 90 of the plugmount 86. The interior of the plug body 92 can include a receptaclehaving a transverse cross-sectional shape that matches the transversecross-sectional shape of the flange 42 of the ferrule hub 30. Theferrule subassembly 26 can be loaded into the back side of the plug body92 and into the receptacle with the tuning mark located at apredetermined position relative to the plug body 92 so that theconnector is tuned. The mating relationship between the transversecross-sectional shape of the flange 42 of the ferrule hub 30 and thereceptacle of the plug body 92 prevents relative rotation between theferrule assembly 26 and the plug body 92. When the ferrule assembly 26is inserted into the back side of the plug body 92, the ferrule 28extends through an opening in a front face of the plug body 92 and afront end surface of the ferrule hub 30 nests within a correspondingseat defined within the plug body 92. The plug body 92 can have anexterior form factor adapted to be compatible with a corresponding fiberoptic adapter. As indicated above, the form factor can be an SC formfactor.

FIGS. 7-14 illustrate a sequence of steps for installing the fieldinstallable subassembly 62 over the factory terminated subassembly 20.Referring to FIG. 7, the factory terminated subassembly 20 is insertedin a rearward to forward direction through the interior of the housing64. It will be appreciated that the seal expansion tube 76 holds theelastomeric sealing sleeve 70 open, and that the inner diameter of theseal expansion tube 76 is large enough to allow the factory terminatedsubassembly 20 to pass through. Once the factory terminated subassembly20 has passed through the housing 64, the casing 50 is removed and theplug locator 78 is inserted over the fiber optic cable 22 at a positionbetween the front end of the housing 64 and the ferrule assembly 26 (seeFIG. 8). The longitudinal slot 80 defined by the plug locator 78 allowsthe fiber optic cable 22 to be laterally inserted into the plug locator78. The insertion process also includes inserting the fiber optic cable22 laterally through the through slot 88 defined by the plug mount 86.Once the fiber optic cable 22 has been centrally located within the pluglocator 78, the plug locator 78 can be inserted into the front end ofthe housing 64. It will be appreciated that a rear portion of the pluglocator 78 fits within the housing 64 and a shoulder 79 abuts against afront end face of the housing 64 (see FIGS. 9 and 26).

With the plug locator 78 in place, the plug body 92 is then coaxiallyaligned in front of the ferrule assembly 26 (see FIG. 10) andsubsequently moved rearwardly relative to the ferrule assembly 26 suchthat the ferrule assembly 26 is received within the interior of the plugbody 92. As indicated above, the ferrule assembly 26 is preferablyoriented at a tuned relation relative to the plug body 92. With theferrule assembly 26 received within the plug body 92, the plug body 92is inserted rearwardly over the plug mount 86 of the plug locator 78. Asthe plug body 92 is moved axially over the plug mount 86, the snap-fitstructures 92 of the plug mount 86 snap within the snap-fit structures94 of the plug body 92 to provide a secure connection. Additionally, thesurface 87 opposes a rear end of the spring 24 so as to function as aspring stop. Thus, the spring 24 is captured between the surface 87 andthe flange of the ferrule hub 30.

Once the plug body 92 is mounted to the plug mount 86, the dust cap 32can be removed from the ferrule 28 and connector can be inserted intothe first port 91 of the hardened fiber optic adapter 90 (see FIG. 16).As the connector is inserted into the first port 91 of the hardenedfiber optic adapter, the ferrule 28 can be received within a ferrulealignment sleeve of the adapter. Additionally, the plug body 92 and thepaddles 82, 84 can mate with corresponding receptacles within theinterior of the hardened fiber optic adapter 90 to ensure that a properrotational orientation is maintained between the hardened fiber opticconnector and the hardened fiber optic adapter 90. Thereafter, thehardened coupling element 64 can be turned relative to the fiber opticcable 22, the housing 64 the plug locator 78 and the plug body 92 suchthat the threads engage the corresponding threads 89 within the hardenedfiber optic adapter. Once the hardened coupling element 64 has beenfully threaded into the hardened fiber optic adapter 90, the sealexpansion tube 76 can be axially pulled from within the interior of theelastomeric sealing sleeve 70 such that the elastomeric sealing sleeveelastically constricts down upon the fiber optic cable 22 to provide aseal with the cable 22.

In certain examples, the seal expansion tube 76 can be cut from thecable 22. In other examples, the seal expansion tube can remain on thecable 22 to provide protection. In the example of FIG. 15, the tube 76can be long enough to extend from the rear of the housing to a duct 101through which the fiber optic cable 22 had been routed.

FIG. 17 shows another kit 160 for a field installable subassembly 162adapted to be mounted over the factory terminated subassembly 20 toconvert the factory terminated subassembly 20 into a hardened fiberoptic connector. Similar to the embodiment of FIGS. 6-14, the hardenedfiber optic connector that results from the kit 160 is adapted to matewith a hardened fiber optic adapter such as the fiber optic adapter 90of FIG. 16. It will be appreciated that while both examples of hardenedconnectors disclosed herein have paddles, other examples may not havepaddles. In certain examples, kits can be utilized so as to convert thefactory terminated subassembly 20 into a hardened fiber optic connectorof the type disclosed at U.S. Pat. No. 7,744,288, which is herebyincorporated by reference in its entirety.

Referring to FIG. 17, the field installable subassembly 162 includes ahardened coupling element 164 having a front end 166 and a back end 168.An elastomeric sealing sleeve 170 of the type previously described ismounted at the back end 168 of the hardened coupling element 164. Atwist-to-lock coupling interface 174 is positioned at the front end 166of the hardened coupling element 64. As depicted, the twist-to-lockcoupling interface 174 is shown as threads. In other examples, othertypes of interfaces such as a bayonet-type interface could be used. Thetwist-to-lock coupling interface 174 in the form of form of threadsextends from the front end 166 of the hardened coupling element 164 toan outer shoulder 175 of the hardened coupling element 164. An annularseal 172 such as a face seal is mounted around the hardened couplingelement 164 adjacent the outer shoulder 175. The annular seal 172 abutsagainst a forwardly facing surface of the outer shoulder 175.

Referring still to FIG. 17, the field installable subassembly 162 alsoincludes a plug body 192 having the same basic construction as the plugbody 92 and a rear housing 177 adapted to be secured to a rear end ofthe plug body 92. In certain examples, the plug body 192 has a snap-fitstructure 194 that engages a corresponding snap-fit structure 179defined by the rear housing 177. The rear housing 177 also functions asa spring stop with the spring 24 being captured between a surface of therear housing 177 and the flange 42 of the ferrule hub 30. The fieldinstallable subassembly 162 further includes a plug locator 178 havingtwo mating pieces between which the plug body 192 and the rear housing177 are mounted. The plug locator 178 includes opposite paddles 182,184. The plug locator 178 also includes a radial shoulder 181 that abutsagainst a front end of the hardened coupling element 164 when the pluglocator 178 is loaded into the hardened coupling element 164. A sealexpansion tube 176 is provided within the back end of the elastomericsealing sleeve 70 to hold the elastomeric sealing sleeve open untilafter the assembly and installation process has been completed.

It will be appreciated that the hardened coupling element 164 functionsas a sealed outer housing. For example, the rear end of the hardenedcoupling element 164 is sealed relative to the fiber optic cable 22 bythe elastomeric sealing sleeve 170 and the front end of the hardenedcoupling element 164 is sealed relative to the fiber optic adapter bythe annular seal 172. In certain examples the annular seal 172 is anaxial face seal. In other examples, annular seal 172 can be a radialseal.

FIGS. 18-24 show an assembly process for assembling the fieldinstallable subassembly 162 over the factory terminated subassembly 20.Referring to FIG. 18, the factory terminated subassembly 20 is initiallyinserted through the interior of the seal expansion tube 176 and throughthe interior of the hardened coupling element 164. As previouslydescribed, the seal expansion tube 176 has an inner diameter that islarger than a maximum outer cross-sectional dimension of the factoryterminated subassembly 20. The seal expansion tube 176 holds theelastomeric sealing sleeve 170 open to a position large enough where thefactory terminated subassembly 20 can readily be passed through thehollow passage of the hardened coupling element 164 without interferencefrom the elastomeric sealing sleeve 170.

Referring to FIG. 19, after the ferrule assembly 26 and spring 24 of thefactory terminated subassembly 20 have passed through the hardenedcoupling element 164 in a rear to front direction, the protective casing50 is removed to expose the ferrule assembly and the spring. The rearhousing 177 is then inserted over the fiber optic cable 22 at a locationbetween the spring 24 and the front end of the hardened coupling element164. It will be appreciated that the rear housing 177 has a longitudinalslot 173 for allowing the rear housing 177 to be readily laterallyinserted over the fiber optic cable 22. As shown at FIG. 20, the plugbody 192 is then coaxially aligned in front of the ferrule assembly 26as shown at FIG. 20. Thereafter, the ferrule assembly 26 is loaded intothe plug body 192 through the back side of the plug body 192 (see FIG.21) and the rear housing 177 is then snapped into the back side of theplug body 192 to capture the spring 24 and the ferrule assembly 26within the interior of the plug body 192. With the ferrule assembly 26mounted within the plug body 192, the ferrule 28 protrudes forwardlythrough the front side of the plug body 192. It will be appreciated thatthe ferrule assembly 26 is preferably loaded in a tuned positionrelative to the plug body 192.

Once the plug body 192 and the rear housing 177 have beeninterconnected, two half-pieces of the plug locator 178 can be matedtogether over the assembled plug body 192 and rear housing 177 such thatthe plug body 192 and the rear housing 177 are captured within theinterior of the plug locator 178. It will be appreciated that theinterior of the plug locator 178 can have a shape that compliments theexterior shape of the plug body 192 and the rear housing 177 such thatthe plug body 192 is securely axially retained relative to the pluglocator 178. U.S. Pat. No. 7,614,797, which is hereby incorporated byreference in its entirety, provides more details about the half-piecesof the plug locator 178.

After the plug locator 178 has been mounted over the plug body 192 andthe rear housing 177, the plug locator 178 is inserted rearwardly intothe front end of the hardened coupling element 164 until the radialshoulder 181 abuts against the front end face of the hardened couplingelement 164. Upon insertion of the plug locator 178 in the hardenedcoupling element 164, the field installable subassembly 162 is fullyinstalled and the ruggedized fiber optic connector is ready to be matedwith the corresponding fiber optic adapter 90. For example, the dust cap32 can be removed and front end of the plug locator 178 can be insertedinto the fiber optic adapter 90 with the paddles 182, 184 and the formfactor of the plug body 192 ensuring that the plug locator 178 isinserted into the fiber optic adapter at the appropriate rotationalorientation. Thereafter, the hardened coupling element 164 is rotatedrelative to the plug locator 178 and the fiber optic cable 22 to engagethe twist-to-lock coupling interface 174 of the hardened couplingelement 164 with the corresponding twist-to-lock coupling interface ofthe fiber optic adapter. In the case of threads, exterior threads of thehardened coupling element 164 thread within corresponding interiorthreads defined by the hardened fiber adapter 90. The threading processcontinues until the annular seal 172 is suitably compressed. Thereafter,the seal expansion tube 176 is removed from within the elastomericsealing sleeve 170 such that the rear portion of the elastomeric sealingsleeve 170 constricts down upon the fiber optic cable 22 to provide aseal about the fiber optic cable 22.

While the field installable subassemblies 62 and 162 have been depictedas ruggedized assemblies, it will be appreciated that non-ruggedizedassemblies could also be used. Thus, the factory terminated subassembly20 can function as a platform upon which any number of differentconnector configuration assemblies can be built.

It will be appreciated that the factory terminated subassembly 20 canalso be referred to as a base-level subassembly or a core subassembly.Additionally, while the subassemblies 62, 162 have been described asbeing field installable, it will be appreciated that such assemblies canalso be assembled in the factory under certain conditions. However, itwill be appreciated that typically the field installable subassemblieswould be installed in the field about a factory terminated subassembly20 after the factory terminated subassembly has been routed through aduct or other structure to a desired optical connection location.

In certain examples, the factory terminated subassembly 20 may furtherinclude a supplemental structure that ensures the factory terminatedsubassembly 20 is installed in the properly tuned position in the field.For example, FIG. 25 shows an alternative the ferrule hub 230 includinga tuning key mount 231 having circumferential position indicators 232 inalignment with circumferential position indicators 235 defined by aferrule hub flange 236. A tuning key 237 can be mounted on the tuningkey mount 231 with a key member 239 of the tuning key 237 positioned ata predetermined rotational location relative to the core offsetdirection (e.g., axially aligned, offset 180 degrees, etc.). Typically,the key member 239 will align with a tuning marking provided on theferrule hub flange 236. When a field installable subassembly is mountedover the factory terminated subassembly in the field, a plug of thefield installable subassembly has a keyway that mates with the keymember 239 of the tuning key 237 so that the ferrule assembly can onlybe inserted in one rotational position relative to the plug. In thisway, tuning is ensured.

From the forgoing detailed description, it will be evident thatmodifications and variations can be made in the devices of thedisclosure without departing from the spirit or scope of the invention.

What is claimed is:
 1. A method of assembling a fiber optic connector,comprising: providing a subassembly including a ferrule at which anoptical fiber is terminated and a ferrule hub mounted to the ferrule,the fiber defining a longitudinal fiber axis; routing the subassemblythrough a duct; after the routing, inserting the subassembly through ahardened coupling element; after the routing, installing a plug locatorabout the optical fiber; after the routing, installing a plug body thatreceives the ferrule and the ferrule hub; and connecting the pluglocator to the plug body.
 2. The method of claim 1, further comprising,before the routing, enclosing the connector subassembly in a casing, therouting including routing the casing enclosing the connector through theduct.
 3. The method of claim 1, further comprising, subsequent to therouting, removing the casing from the subassembly.
 4. The method ofclaim 3, wherein the removing is performed after the inserting thesubassembly through a hardened coupling element.
 5. The method of claim1, wherein the plug locator includes a plug mount to which the plug bodyis connected.
 6. The method of claim 1, wherein the installing the pluglocator is performed by laterally installing, relative to the axis, thefiber through a slot defined by the plug locator.
 7. The method of claim1, wherein the installing the plug locator is performed byinterconnecting two pieces of the plug locator to each other about thefiber.
 8. The method of claim 7, wherein each of the two pieces is ahalf-piece of the plug locator.
 9. The method of claim 1, wherein theplug locator includes a pair of opposite paddles.
 10. The method ofclaim 1, further comprising, after connecting the plug locator,installing the plug body in a fiber optic adapter.
 11. The method ofclaim 1, wherein the plug body has an SC type form factor.
 12. Themethod of claim 1, wherein the hardened coupling element is installed toturn about the fiber axis, the hardened coupling element including atwist-to-lock coupling interface.
 13. The method of claim 1, wherein therouting includes pushing or pulling the subassembly through the duct.14. The method of claim 1, further comprising installing an elastomericsealing sleeve on the plug locator.
 15. The method of claim 1, furthercomprising, before the connecting the plug locator to the plug body,connecting a rear housing to the plug body to axially capture the springbetween the plug body and the rear housing.
 16. The method of claim 15,further comprising laterally installing, relative to the axis, theoptical fiber in the rear housing through a slot defined by the rearhousing.